[centurion316]

I am assuming that the stone walls in the picture are not neolithic, but later. Am I wrong?

[SunkenCiv]

:^) Ya build with what ya have. Post-Roman construction in Britain was wattle-and-daub walls and thatch roofs, that may have been in introduction by the Anglo-Saxons, but was likely commonplace for a really, really long time, and not just in the British Isles. When your house gets burned down a few times, and/or you have some cold winters, stone looks like a better idea. Also, the remains of mud huts tend to be a bit ephemeral -- more of them at the time, but the remains are more fragile as well as easily missed.

[Harmless Teddy Bear]

The default material humans build with is wood but in places where wood is scarce they tend to use stone to save the wood for other uses. Wattle and dab does not require really big trees so that is used where there is an abundance of low scrub. Also Ireland is a tad bit on the damp side so building the lower portion of the house with stone would help prevent rot.

They didn't have nice big rot resistant chestnut trees to build with as they did in the US.